Prevalence of genotypic drug resistance among a cohort of HIV-infected newborns.

A retrospective, blinded study was conducted to examine the prevalence of antiretroviral drug resistance among a cohort of HIV-infected infants born in 1998 and 1999 in New York State. The earliest available HIV-positive specimen was tested. Most samples were from infants younger than 60 days of age. Genotype data were generated for the protease and reverse transcriptase genes of HIV-1 proviral DNA from 91 infected infants. Eleven infants (12.1%) had provirus with mutations associated with drug resistance, with all three classes of antiretroviral drugs represented. Two infants (2.2%) had mutations associated with resistance to two classes of antiretrovirals. Perinatal antiretroviral drug exposure was examined; it was not found to be significantly associated with the presence of resistance mutations. However, for those infants who had perinatal antiretroviral exposure and genotypic evidence of drug resistance to HIV, the mutations that were detected correlated with at least one antiretroviral from the perinatal period. The prevalence of genotypic drug resistance among this infant cohort is comparable with that found among recently infected adults. These results suggest that resistance testing should be strongly considered for perinatally infected infants, at the earliest possible time point, to avoid use of antiretroviral drugs to which the infant has preexisting resistance.